Davis Allen Cripe, 16, drank a latte from McDonald's, a large Mountain Dew soda, and a highly caffeinated energy drink in just under two hours, said Gary Watts, the coroner of Richland County, South Carolina.
Watts told Reuters by phone that physicians on his staff determined that Cripe died from a "caffeine-induced cardiac event causing a probable arrhythmia".
It was likely that caffeine would not have been seen as a factor in his death if it had not been for witnesses who could tell officials what Cripe had to drink before he collapsed during a high school class, Watts said.
He said the primary witness to what Cripe drank could not definitely say what brand of energy drink he had but said it was from a container the size of a large soft drink.
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"The energy drink was basically chugged," Watts said.
Watts said Cripe was considered a healthy teenager and did not have an undiagnosed heart condition. There was no sign of a heart condition in an autopsy of the 16-year-old.
"This is not a caffeine overdose," Watts said. "We're not saying that it was the total amount of caffeine in the system, it was just the way that it was ingested over that short period of time, and the chugging of the energy drink at the end was what the issue was with the cardiac arrhythmia."
Davis weighed a little more than 90 kg but would not have been considered morbidly obese, Watts said. He died about an hour after collapsing in a high school near Columbia, South Carolina.
Cripe may have had the same amount of caffeine on another day and been all right, Watts said.
"We're not trying to speak out totally against caffeine," Watts said.
"We believe people need to pay attention to their caffeine intake and how they do it, just as they do with alcohol or cigarettes."
The Mayo Clinic said in a March report that up to 400 milligrams of caffeine a day "appears to be safe for most healthy adults".
According to caffeineinformer.com, a McDonald's latte has 142 milligrams of caffeine, a 20-ounce Mountain Dew has 90 milligrams, and a 16-ounce energy drink can have as much as 240 milligrams.
